Type 212 Multi Purpose Submarine - Design
Air-Independent Propulsion" (AIP) submarines can be used to telling effect for both short- and medium-range missions. AIP dramatically expands the tactical "trade-space" for diesel-electric submarines. If conditions permit, they can transit rapidly on the surface with-out unduly expending the wherewithal for superior underwater performance. Submerged, they can opt for a long, slow, silent patrol that keeps their batteries fully charged and thus capable of powering speed bursts of significant duration. And by carefully husbanding their resources, they can revert again to slow-speed operation and repeat the cycle several times over weeks of submergence.
The ship was built in a one and a half-hull system, and its strong hull is made of non-magnetic steel, which not only reduces the risk of detecting the ship, but above all enables its safe operation in areas with high mine risk. The use of non-magnetic steel also optimizes the demagnetization system to the necessary minimum and saves valuable electricity. The manufacturer declares that the magnetic signature of the 212A ships is less than 40 percent. this value in the case of type 214 ships. For the construction of the light (outer) hull, composite materials were used from which the deck plating, cover of hydroacoustic stations, rudders and depth controls were used.
The the first AIP system to enter regular submarine service were the Swedish Navy's three Gotland-class submarines, which each used two Stirling cycle engines as an adjunct to their main diesel-electric engineering plants to provide underwater endurance up to several weeks. Class 206A influenced the design of the German submarine already high flexibility for operations in shallow and narrow waters with lowest snorkel times for battery charging. The development of detection technologies and the increasing number of submarinejagdmittel, as well as the advanced area of the application required the development of the new class 212 A. In the bow part of the ship there are 6 533 mm torpedo tubes. (the ship can carry a total of 12 torpedoes), which also allow the integration of missiles of various types.
The most prominent feature of the Type 212 is an air-independent propulsion system using a silent hydrogen/oxygen fuel cell system that makes the submarine more difficult to detect and inceases submersion time. The Type 212's hybrid diesel-electric and air-independent fuel-cell propulsion system meets a vital requirement for low detectability. The efficiency of these fuel cells is very high compared to the diesel generator. It is approximately 65%. This means that 65% of applied energy, which is in the hydrogen, can be converted into electricity. The losses, E.g. due to friction/heat amount to only 35%. At best, good diesel generators have an efficiency of about 30%. Since the voltage can reach a single fuel cell is limited, be installed in several fuel cells. Such a module can then generate the voltage required and the desired amount of electricity connected in parallel several modules.
The greatest challenge for fuel-cell AIP systems lies in storing the reactants. Although oxygen can be handled with relative safety as LOX, storing hydrogen onboard as a liquid or high-pressure gas is very dangerous. One solution is to carry the hydrogen in metal hydride accumulators, at low pressure and ambient sea temperature. (A metal hydride is a solid compound of hydrogen and metallic alloy, in which individual hydrogen atoms occupy interstitial positions in the host metal's crystalline lattice. By manipulating temperature and pressure, hydrogen gas can be absorbed or released at will.) Another, less efficient, approach is to generate gaseous hydrogen from a stored liquid hydrocarbon such as diesel fuel, kerosene, or methanol. This requires an auxiliary device called a "reformer," in which a mixture of hydrocarbon and water is vaporized and superheated under pressure to yield a mixture of hydrogen and carbon dioxide.
A noiseless propeller is driven by a low-noise, high-performance, permament-magnet motor. The reactants for the fuel cell (hydrogen and oxygen) will be stored in the after part of the boat between the pressure hull and an outer, free-flooding hull. The low-detection-probability requirement will also be met by reducing the boat's acoustic, magnetic, radar, and visual signatures and by minimizing its sonar target strength (against active detection) and sonar target level (against passive detection). The pressure hull, made of high-strength nonmagnetic steel, is optimized for hydrodynamic properties and maneuverability.
PEM (Polymer Electrolyte Membrane) fuel cells are known for their efficient conversion of hydrogen (as fuel) and oxygen into electrical energy. Optimised for specific requirements in submarines, they will be the key component for electricty generation in future conventional submarines. Siemens has developed and is manufacturing two different types of PEM fuel cell modules, one type for the German and Italian U 212 submarines and antoher for the U214 submarine which will be used by the Hellenic and the South Korean navy.
The 1,840-ton German and Italian U 212-class submarines use nine PEM fuel-cell modules each nominally rated at 34 kilowatts, to yield a total of approximately 300 kilowatts (400 horsepower). With metal-hydride hydrogen storage, the system is predicted to yield 14 days submerged endurance and the ability to run up to eight knots on the fuel cells alone. Siemens developed a next-generation PEM module rated at 120 kilowatts, and two of these are incorporated into HDW's 1,860-ton U 214 boats, planned as export successors to the U 212 series.
Siemens marine & shipbuilding’s polymer electrolyte membrane (PEM) fuel cells are the wave of the future for external air-independent electric energy generation in submarines. As the cells need only hydrogen and oxygen as fuel, dives can be significantly prolonged. This makes submarines equipped with these low-temperature fuel cells far superior to conventional submarines, which must surface fairly often to recharge their batteries. These designs are much more efficient and emit no exhaust whatsoever. Thanks to their electrochemical mechanism of action, which creates only water and heat in addition to electricity, the PEM fuel cell creates zero noise. Its robust, low-signature and nonmagnetic design was specially created for long-term use and has an expected service life of many years – and all in a very low-maintenance package.
The fuel cell system permits submerged operations for up to one month without snorkeling. The design itself is very hydrodynamically clean, which suggests a high maximum speed (>20 kts). Using the X-helm for the first time, the German Navy will also improve agility. New stainless and a-magnetic steel for the pressure hull could allow dives of over 300 m.
The Type 212's two decks of crew space mean that the days of the "warm bunk" belong to the past. The commander has his own cabin with a door. The boat is so spacious that change dividing of the interior arrangement is no longer necessary for reloading the weapons. The towed array is mounted in the conning tower. The X-tail rudders would guide it directly into the propellor if the steel ropes weren't strung from the rudder tips.
|
NEWSLETTER
|
| Join the GlobalSecurity.org mailing list |
|
|
|
